Gasoline? NatGas? Our car lets you choose, GM says

General Motors, the largest U.S. carmaker, is planning to become the first to sell a bi-fuel-powered car that can run on either regular gasoline or compressed natural gas. CEO Dan Akerson will unveil GM's plans Tuesday afternoon at the Securing America's Future Energy Conference in Washington.

"A natgas-powered car is something we've been considering and working on for some time," said a source within General Motors. "We won't sell a ton of these cars at first, but it's a good start."

GM is not putting a price tag on the bi-fuel car, which goes on sale next summer. The automaker is projecting it will have a range of 150 miles using CNG and another 350 miles using gasoline. The driver will be able to switch between the two fuel tanks while driving.

Akerson has long been a proponent of developing natgas-powered vehicles, and a few weeks ago GM said it plans to sell bi-fuel compressed natural gas versions of the 2015 Chevrolet Silverado and GMC Sierra pickups. While the automaker has yet to announce a price for those trucks, previous versions of CNG-powered pickups have gone for about $11,000 more than standard, gasoline-powered models.

Those costs, along with the lack of public CNG refueling stations, are reasons automakers have been slow to expand their lineups to include natgas-powered vehicles. There are only 650 CNG stations in the U.S. open to the public, versus more than 168,000 gas stations.

The selling points of converting Americans to natgas vehicles are numerous. They have been shown to reduce emissions by as much as 80 percent compared with standard gas-powered engines.

Meanwhile, the supply of natural gas is so plentiful in the U.S. that it is less expensive than regular gas. Right now, the average price for a gallon of regular is $3.35 according to AAA, while the equivalent of a gallon of CNG sold for $2.14 this summer.

Still, GM knows demand for CNG-powered cars and trucks is likely to be limited until more natgas refueling stations are built.

"Natgas-powered cars may not be big sellers, but this is the trend of the future. We want to make sure we're ready when natgas cars eventually take off," said a GM executive familiar with the automaker's plans.